• Category
  • Length Range
    84-121 µm
  • Width Range
    20-26 µm
  • Striae in 10 µm
  • Reported As
    Cymbella stuxbergii var. siberica (Foged 1981, p. 75, plate L, fig. 1)



Valves are moderately dorsiventral with arched dorsal margins and weakly concave ventral margins with a slightly tumid center. Axial area is about 3-4 times wider than the raphe and follows the median line of the valve. Central area is large and elliptic in shape. From 6 to 9 isolated stigmata form a straight or slightly curved line along the apical axis on the ventral side of the central nodule and some distance from the middle striae. The raphe is lateral and becomes filiform near the proximal and distal ends. Proximal raphe ends are straight with expanded tips. Distal raphe ends are hooked at nearly right angles toward the dorsal margin. Striae are radiate throughout. Areolae are easily resolved in LM and number 14-18 in 10 µm.


Cymbella amplificata was recently collected from two lakes in King County, Washington by Lisa White, a volunteer with Adventurers and Scientists for Conservation. These are the first confirmed records for this species in the lower 48 states. The type locality is Lake Baikal and it has also been reported from other sites in Siberia. Foged (1981) reported it from Alaska (as Cymbella stuxbergii var. siberica). According to Krammer (2002) this diatom prefers oligotrophic waters with a low to average electrolyte content.

Glacier Lake
Credit: Lisa White, Adventurers and Scientists for Conservation
Glacier Lake, King County, Washington—one of only two lakes in the lower 48 states that is known to support a population of Cymbella amplificata.

Original Description

  • Basionym
    Cymbella stuxbergi var. intermedia
  • Author
    Wislouch 1924

Original Images

Cymbella stuxbergi var. Intermedia orig illua
Cymbella stuxbergi var. intermedia orig illus

Cite This Page

Bahls, L. (2012). Cymbella amplificata. In Diatoms of North America. Retrieved April 21, 2024, from https://diatoms.org/species/cymbella_amplificata


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbella amplificata from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.